Mechanism for precision switches



Aug. 31, 1948. 'E. MILLER 4 uncmmzsu Fox, PRECISION swn'cnss Filed April 3,1946

Anm'

Patented Aug. 31, 1948 UNITED STATES PATENT OFFICE 2,448,230 r n amonamsm ron PRECISION swrrcnss Edwin August Miller, Fairiield, Conn.

Application April 3, 1946, Serial No. 659,191

3 Claims. (!.200-6'7) This invention relates to mechanism for precision switches, including switches adapted for alternate electric currents;

The objects of the invention are to provide a snap action switch which maintains -a constant maximum contact pressure up to the breaking point; to provide a switch having actuating, means including a fiat springto which resilient properties are imparted whil a portion of the spring is held in a predetermined manner; and to provide a switch the mechanism of which is compact,

- permanent connection with the inner end of the with the least required exertive pressure of operation, and adapted for a reduced are of oscillation.

Referring to the accompanying drawing, the Figure 1 is an erect elevation of the device, illustrating the insulation casing in cross-section and the mechanism in a maintained at-rest position; Figur 2 is a similar elevation but illustrating the mechanism in an operated position; Figure 3 is a top surface view of the oscillating member fixedly supported at oneend to the casing, the casing illustrated in outline; Figures 4 and 5 are diagrammatic layouts of different mechanical positions of the oscillating member and associated parts; and

Figure 6 is a detail illustrated in perspective.

With more particular reference to the accompanying drawing, in which there is illustrated one form only of the invention with regard to the novel mechanism and manner by which the improvement herein set forth is accomplished. Other forms within the scope of the invention may be obvious.

The invention herein set forth is an improvement of mechanism disclosed and claimed in a previous application for patent, Serial Number 583,049 filed by me on March 16, 1945, now Patent No. 2,428,172, issued Sept. 30, 1947, and in which an opening of an oscillating member contains a tongue. and its connection with a leaf spring through the medium of a rigid link, of greater length than that of the opening. The improvement, about to be herein set forth, eliminates the rigid link.

The casing I, of insulation material, illustrated in cross-section, accessibly provides wire connection terminals 2, 3 and 4, adapted for electric terminal 4, as illustrated by the Figures 1 and 2,

carries at its opposite end the upper and lower,

superposed contact surfaces 9 and 10, respectively,

adapted for alternate engagements, with the fixed contacts 5 and 6 in maintained at rest and operated positions of the oscillating body memher 1. The tongue 1 I is illustrated as integral with the body member 1 and pendulously formed by being cut on three sides from within the central surface-length thereof although, if desired, the tongue II may be a separate piece of sheetmetal set within the opening 1A of the body member 1 having the fourth side out out, the separate piece being fixed to the body member 1. A-thin leaf spring I2 is secured at its upper end to the insulation casing l and the free lower end is movably held within the slot iii of the casing l.

' operated by means of manual pressure of. the

wiringinot illustrated) for the establishment of member I, one end of which is anchored, as at l,

within the casing I where it is provided with a Said leaf spring I2 is provided at its'side edges with the open recesses l4 within which to fit the extended lugs l5 of the tongue extremity as a means of hinged assembly. The tension of the leaf spring I2 is exerted outwardly against the tongue II in one direction only tomaintain the tongue normally buckled upin an over-centering position relative to the body 1 of the oscillating member. 7

As illustrated by the Figure 1, the oscillating body member 1 and connected parts of the precision switch mechanism are held at rest in said over-centering position. In the Figure 2, the mechanized parts are illustrated as having been thumb it placed upon the push element I! whereby the tongue II is depressed below theoscillating body member I, to an undercentering position.

Due to the over-all length of the combined tongue I l and leaf spring l2, being slightly greater in length than the opening 1A of the oscillating member I in which opening 1A they operate, the

tongue H is forced to buckle with regard to the oscillating body member I. In the forced movement by means of pressure of thethumb, or similar means, upon the push element, the." overcentered tongue is compelled to leave such overcentering position, passing throughv a center to an under-centering whereby the body member is sufliciently distorted so that the transition is one of sudden snap action wherein thefree end-of the oscillating body member I, carrying the superposed contacts vll and ill, engages its contact 8 with the fixed contact 5 supported by the casing l, which contact engagement is ,maintained as H long as manual pressure remains upon the push element II, as illustrated by the Figure 2. Withaesaaso means by which the precision switch is operated to one of its extreme positions, it is to be understood 'thatsuch movement of operation is adapted to be accomplished by any other means, such as when the invention is applied as a part of an automatic means adapted for precision control in mass production of an article, in which case the switch may be mechanically, operated as a Part of such means.

In the Figures 4 and 5, it will be noted that the full line I designates the body of the oscillating member, and the dotted line II represents the tongue member. In the Figure 5 the tongue I I is shown overcentered with relation to the body I, while, in the Figure 5 the tongue II is shown as under-centered. Such positions of the tongue ii determine engagements oi the contacts I and II carried by the body member I relative to the fixed contacts 8 and 8.

It will be noted further that, in the Figures 1 and 4, the tongue II is permanently bent upwardly, at I IA, to normally maintain the tongues upwardly, buckled position engaged with the extremity "A of the unoperated push element I1, and the contact O of the distorted body member I normally engaged with the fixed contact I. In the Figures 2 and 5, the tongue II is shown in operated position with the tongue ll downwardly buckled and engaged between the extremity "A of the manually maintained push element I! and the extremity of the fixed stop II, and the contact III of the distorted body 'member I engaged with the fixed contact 5. However, as soon as the manual pressure is removed from the push element II, the tongue ii and the distorted body member I snaps back to their normal positions, as illustrated by the Figures 1 and 4.

It is to be understood that, while the tongue II is herein illustrated as positioned within the central opening IA of the body member I, thetongue Il may just as well be positioned marginally with regard to a body member.

I claim:

1. A snap-acting control mechanism for .a precision switch. the mechanism comprising a sheet-metal oscillating member of which one end is fixed to a base and the opposite end is movable along an 'arc between two fixed stops, said member having an elongated opening therethrough: a resilient tongue positioned within said opening and fixed atone end to said oscillating member; an actuator movably mounted upon said base for movement along a direct plane intersecting the plane of the oscillating member and having an extremity resting down upon an intermediate portion of said tongue; an arcuate-shaped spring member both ends of which engage a base support upon a surface plane which is parallel to said intersecting plane, the arcuate portion of said spring member hingedly engaging the free extremity of said tongue in such manner that the spring member's compressive force maintains said tongue under compression to maintain the intermediate portion ofsaid tongue bowed either above or below said oscillating member thereby determining the position of the contacts, carried by said oscillating member in a snap-acting movement, with respect to either of said fixed Q stops.

' base'and having a hinged connection with the 2. A snap-acting control mechanism for a precision switch, the mechanism comprising an oscillating member of which one end is fixed to a base and the opposite end is movable along an are between two fixed stops, said member having an elongated opening therethrough; a resilient tongue positioned within said opening and having one end fixed tooscillating member; an actuator movably mounted upon said base for movement along a direct plane intersecting the plane of the oscillating member and having an extremity resting down upon an -intermediate portion of said tongue; a spring supported by said free end of said tongue in such manner that the springs compressive force maintains said tongue under compression maintaining the intermediate portion of said tongue bowed either above or below said oscillating member thereby determining the position of the contacts, carried by the oscillating member in a snap-acting movement, with respect to either of the fixed stops.

3. An oscillating member of a. snap-acting control mechanism for a precision switch, said member comprising a flexible body of which one end is supported by a base and the other end being provided with contact surfaces; a tongue secured at one end to said body member; a spring supported by said base remote from said contact surfaces and having a hinged connection with the free end of said tongue, said spring exerting a compressive force along the plane 01' the oscillating member against the extremity of said tongue, and the overall length of the connected tongue and spring being greater than the space between the place of securement of said tongue to said body member andsthe supporting base of said spring; and an actuator movably mounted upon said base for movement along a direct plane intersecting the plane of the oscillating member and having an extremity resting upon the intermediate portion of said tongue.

' EDWIN AUGUST MILLER.

REFERENCES CITED UNITED STATES PATENTS Name Date 'Riche Aug. 22, 1939 Number 2,170,767 

